The Archives of General Psychiatry just published a study by John Ioannidis which basically says that for whatever reason, studies that say that brain volumes are different in different psychiatric disorders are more likely to be published. Ioannidis has shown similar meta-research type findings before in other fields already (see this article for example), and I highly doubt anyone is really surprised by this finding. Still, it’s cool to see this issue being acknowledged by a relatively high-profile journal like Archives.
Basically, Ioannidis takes a few meta-analyses that have examined “brain volume abnormalities” in different psychiatric disorders from 2006-2009, calculates the number of comparisons across studies that would be expected to have positive results based on statistical power, and then checks that against the actual number of positive findings reported in those studies. To make a long story short, whether he slices and dices it by disorder or by brain structure, studies were largely biased towards reporting statistically significant findings.
Now what would be really nice is if Archives (and other psychiatry journals) actually did something with this finding instead of continuing to publish articles that are basically just neurobabble.
John Ioannidis (2011). Excess Significance Bias in the Literature on Brain Volume Abnormalities Archives of General Psychiatry